1. Field of the Invention
The present invention relates to optical plates, and particularly, to an optical plate used in a backlight module of a liquid crystal display device.
2. Discussion of the Related Art
In a liquid crystal display device (LCD device), liquid crystal is a substance that does not itself illuminate light. Instead, the liquid crystal relies on light received from a light source to display information. In the case of a typical liquid crystal display device, a backlight module powered by electricity supplies the needed light.
FIG. 8 depicts a backlight module 100. The backlight module 100 includes a frame 11, a reflective plate 12, a plurality of lamps 13, a light diffusion plate 14, a prism sheet 15, and an upper light diffusion film 16. The frame 11 includes a bottom frame 112, and an upper frame 116. The bottom frame 112 defines a receiving chamber 114. The lamps 13 are aligned above the reflective plate 12 in the receiving chamber 114. The reflective plate 12 is positioned on a base of the bottom frame 112. The light diffusion plate 14, the prism sheet 15, and the upper light diffusion film 16 are positioned on the bottom frame 112 over the receiving chamber 114 in that order. The upper frame 116 serves as a binder for fixing or holding the light diffusion plate 14, the prism sheet 15, and the upper light diffusion film 16 tightly to the bottom frame 112.
In assembling, firstly, the reflective plate 12 is positioned on the base of the bottom frame 112. Secondly, the lamps 13 are regularly disposed in the receiving chamber 114 of the bottom frame 112. Thirdly, optical elements, such as the light diffusion plate 14, the prism sheet 15 and the upper light diffusion film 16, are respectively positioned on the bottom frame 112 over the receiving chamber 114, in that order. Finally, the upper frame 116 is positioned on the upper light diffusion film 16 and fixed to the bottom frame 112. However, the process of fixing the optical elements respectively on the bottom frame 112 requires high precision and costs time. In addition, this process may easily damage or scratch the optical elements. Thus, the backlight module 100 is unduly complicated in assembling and therefore costly to manufacture.
What is needed, therefore, is a new optical plate and a backlight module using the optical plate that can overcome the above-mentioned shortcomings.